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/* ISC license. */
#include <sys/uio.h>
#include <string.h>
#include <stdint.h>
#include <errno.h>
#include <signal.h>
#include <skalibs/types.h>
#include <skalibs/error.h>
#include <skalibs/strerr.h>
#include <skalibs/genalloc.h>
#include <skalibs/sig.h>
#include <skalibs/tai.h>
#include <skalibs/djbunix.h>
#include <skalibs/iopause.h>
#include <skalibs/textmessage.h>
#include <skalibs/textclient.h>
#include <s6-dns/s6dns.h>
#include <s6-dns/skadns.h>
typedef struct dnsio_s dnsio, *dnsio_ref ;
struct dnsio_s
{
size_t xindex ;
s6dns_engine_t dt ;
uint16_t id ;
} ;
#define DNSIO_ZERO { .xindex = 0, .dt = S6DNS_ENGINE_ZERO, .id = 0 }
static genalloc g = GENALLOC_ZERO ; /* dnsio */
static inline void dnsio_free (dnsio *p)
{
s6dns_engine_free(&p->dt) ;
}
static void dnsio_remove (size_t i)
{
size_t n = genalloc_len(dnsio, &g) ;
dnsio *a = genalloc_s(dnsio, &g) ;
dnsio_free(a + i) ;
if (--n) a[i] = a[n] ;
genalloc_setlen(dnsio, &g, n) ;
}
static void fail (size_t i)
{
dnsio *p = genalloc_s(dnsio, &g) + i ;
char pack[3] ;
uint16_pack_big(pack, p->id) ;
pack[2] = p->dt.status ;
dnsio_remove(i) ;
if (!textmessage_put(textmessage_sender_x, pack, 3))
strerr_diefu1sys(111, "textmessage_put") ;
}
static void answer (char c)
{
if (!textmessage_put(textmessage_sender_1, &c, 1))
strerr_diefu1sys(111, "textmessage_put") ;
}
static int parse_protocol (struct iovec const *v, void *context)
{
char const *s = v->iov_base ;
uint16_t id ;
if (v->iov_len < 3) strerr_dief1x(100, "invalid client request") ;
uint16_unpack_big(s, &id) ;
switch (s[2]) /* protocol parsing */
{
case 'Q' : /* send a query */
{
dnsio *p ;
size_t n = genalloc_len(dnsio, &g) ;
tain limit ;
uint16_t qtype ;
if (v->iov_len < 21)
strerr_dief1x(100, "invalid client request") ;
if (!genalloc_readyplus(dnsio, &g, 1))
{
answer(ENOMEM) ;
break ;
}
p = genalloc_s(dnsio, &g) + n ;
p->dt = s6dns_engine_zero ;
uint16_unpack_big(s + 3, &qtype) ;
if (memcmp(s + 5, "\0\0\0\0\0\0\0\0\0\0\0", 12))
tain_unpack(s + 5, &limit) ;
else tain_add_g(&limit, &tain_infinite_relative) ;
if (!s6dns_engine_init_g(&p->dt, &s6dns_rci_here.servers, 1, s + 17, v->iov_len - 17, qtype, &limit))
{
answer(errno) ;
break ;
}
p->id = id ;
genalloc_setlen(dnsio, &g, n+1) ;
answer(0) ;
break ;
}
case 'q' : /* cancel a query */
{
dnsio *a = genalloc_s(dnsio, &g) ;
size_t n = genalloc_len(dnsio, &g) ;
size_t i = 0 ;
for (; i < n ; i++) if (a[i].id == id) break ;
if (i >= n)
{
answer(ENOENT) ;
break ;
}
dnsio_remove(i) ;
answer(0) ;
break ;
}
default : strerr_dief1x(100, "invalid client request") ;
}
(void)context ;
return 1 ;
}
int main (void)
{
PROG = "skadnsd" ;
if (ndelay_on(0) == -1 || ndelay_on(1) == -1)
strerr_diefu1sys(111, "set fds nonblocking") ;
if (!sig_altignore(SIGPIPE))
strerr_diefu1sys(111, "ignore SIGPIPE") ;
tain_now_set_stopwatch_g() ;
if (!s6dns_rci_init(&s6dns_rci_here, "/etc/resolv.conf"))
strerr_diefu1sys(111, "initialize structures from /etc/resolv.conf") ;
{
tain deadline ;
tain_addsec_g(&deadline, 2) ;
if (!textclient_server_01x_init_g(SKADNS_BANNER1, SKADNS_BANNER1_LEN, SKADNS_BANNER2, SKADNS_BANNER2_LEN, &deadline))
strerr_diefu1sys(111, "sync with client") ;
}
for (;;)
{
tain deadline = TAIN_INFINITE ;
size_t n = genalloc_len(dnsio, &g) ;
dnsio *a = genalloc_s(dnsio, &g) ;
iopause_fd x[3 + n] ;
int r ;
x[0].fd = 0 ; x[0].events = IOPAUSE_EXCEPT | IOPAUSE_READ ;
x[1].fd = 1 ; x[1].events = IOPAUSE_EXCEPT | (textmessage_sender_isempty(textmessage_sender_1) ? 0 : IOPAUSE_WRITE) ;
x[2].fd = textmessage_sender_fd(textmessage_sender_x) ;
x[2].events = IOPAUSE_EXCEPT | (textmessage_sender_isempty(textmessage_sender_x) ? 0 : IOPAUSE_WRITE) ;
for (size_t i = 0 ; i < n ; i++)
{
size_t j = 3 + i ;
s6dns_engine_nextdeadline(&a[i].dt, &deadline) ;
x[j].fd = a[i].dt.fd ;
x[j].events = 0 ;
if (s6dns_engine_isreadable(&a[i].dt)) x[j].events |= IOPAUSE_READ ;
if (s6dns_engine_iswritable(&a[i].dt)) x[j].events |= IOPAUSE_WRITE ;
a[i].xindex = j ;
}
r = iopause_g(x, 3 + n, &deadline) ;
if (r < 0) strerr_diefu1sys(111, "iopause") ;
if (!r)
{
for (size_t i = 0 ; i < genalloc_len(dnsio, &g) ; i++)
if (s6dns_engine_timeout_g(&a[i].dt)) fail(i--) ;
continue ;
}
if (x[1].revents & IOPAUSE_WRITE)
if (!textmessage_sender_flush(textmessage_sender_1) && !error_isagain(errno))
strerr_diefu1sys(111, "flush stdout") ;
if (x[2].revents & IOPAUSE_WRITE)
if (!textmessage_sender_flush(textmessage_sender_x) && !error_isagain(errno))
strerr_diefu1sys(111, "flush asyncout") ;
for (size_t i = 0 ; i < genalloc_len(dnsio, &g) ; i++) if (x[a[i].xindex].revents)
{
int r = s6dns_engine_event_g(&a[i].dt) ;
if (r < 0) fail(i--) ;
else if (r)
{
char pack[3] ;
struct iovec v[2] = { { .iov_base = pack, .iov_len = 3 }, { .iov_base = s6dns_engine_packet(&a[i].dt), .iov_len = s6dns_engine_packetlen(&a[i].dt) } } ;
uint16_pack_big(pack, a[i].id) ;
pack[2] = 0 ;
if (!textmessage_putv(textmessage_sender_x, v, 2))
strerr_diefu1sys(111, "textmessage_put") ;
dnsio_remove(i--) ;
}
}
if (!textmessage_receiver_isempty(textmessage_receiver_0) || x[0].revents & IOPAUSE_READ)
{
if (textmessage_handle(textmessage_receiver_0, &parse_protocol, 0) < 0)
{
if (errno == EPIPE) break ; /* normal exit */
strerr_diefu1sys(111, "handle messages from client") ;
}
}
}
return 0 ;
}
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